1. FIELD OF THE INVENTION:
The invention concerns apparatus for the heat treatment of industrial and domestic refuse as well as plastics waste containing thermoplastics material, the waste having been previously comminuted to a processable size.
2. DESCRIPTION OF THE PRIOR ART:
Because of the ever-increasing burden on the environment the processing and re-use of waste and refuse of all kinds of material assumes ever greater significance. However, difficulties arise in the separation of the components of waste according to type. It is particularly difficult to sort from the waste those components which are of plastics and to re-use them in a convenient way.
Thus, for instance, it is known from German accepted specification No. 2,061,574 to sort paper, textile materials, glass and metal from refuse and to sort the remainder by hand into plastics as well as a part which is mainly of organic components. The plastics material is then comminuted, heat treated and finally processed into a plastics product, the plastics material not regeneratable by heat being incorporated as a filler into the plastics product.
This process ensures an expedient mode of re-utilisation of the plastics materials but on the other hand it is relatively labour-intensive. In particular, it is nowadays difficult to procure workmen to sort waste by hand.
From German published application No. 21 07 268 it is known to sort previously comminuted plastics parts according to the buoyancy principle, to granulate the sorted plastics materials and then, as far as possible, to press them into new plastics parts. Although this process leads to almost pure plastics parts as regards the type of plastics, it has nevertheless the disadvantage that the sorting involves significant investment costs.
Finally, it is already known from German published application No.21 45 310 to comminute plastics waste and to cover or encapsulate its parts with a suitable binding material, for instance a cement mixture or water glass, and to utilise the covered or encapsulated parts as filling and insulating material for finished structural products. In using this process the waste plastics can be re-utilised in a relatively simple way. It is however a precondition that the plastics waste should not contain other types of waste. The thus treated plastics material is in addition usable to a limited extent only.